Eccentric drive cone loud speaker



Sept. 15, 1931- A. MCL. NICOLSON ECCENTRIC DRIVE GONE LOUD SPEAKER FiledMarch 11, 1927 NTO AN NI lNVE ALEXANEER McLE AQO RNEY Patented Sept. 15,1931 UNITED STATES :iATENT' Q'FFIEE ALEXANDER MQLEAN N'IGVQLSQN, 01 NEWYQBRN- Y. ASSIGNQR, BY MESNE ASSIGN- MENTS, 'ro FEDERAL TELEGRARHGOMPANY, ,a conrona rrpn or CALIFORNIA ECCENTRIG DRIVE CONE LOUD SPEAKERApplication filed March 11., 1987. Serial No. 174,493.

"This invention relatesto sound reproducaingand radiating apparatus andmore particularly to such apparatus designated as loud speakers andcomprising ,-a relatively large rigid diaphragm exposed'on one sidesatleast to unconfined air and driven by mechanical vibrationscorresponding %to the soundsto'be reproduced.

it is an-object of this :invention to provide an improved device of theclass described, so arranged that a diaphragm having an apexsymmetrically disposed with reference to its periphery, may be caused tovibratein a different manner to that in which .it would ,vibrate werethe driving force impressed {011 its apex, whereby a different frequencyresponse, and character of sound, may :be obtalined.

It is a further object of this invention to provide improved apparatusof the class described, so arranged asitohave pa-Itsparticnlarly adaptedto respond to 'high frequencies and other parts particularly adapted torespond to low frequencies connected tgether in such a manner that thesound vibrations may "be impressed between :the said parts.

'It is stilla further object ofmy invention to provide generallyimproved apparatus of the class described.

Figure 6 isa irontlelevation of a still further modified formlof myinvention,

In accordance with my invention, I pro- V ll 1 JQla'tively large rigiddiaphragm, having one side at least exposedto unconfined air. one formof myinvention, the diazpl lflgln may be in the form of a large andrigid cone or as in another form thereof, it maybe in a fOrmhaving 2cones of different sizes, having .their apexes facing in oppositedirections, and forming'a circular line of inate sec ion- The drivingforce is applied ,to :the dia phragm, not at the ;apex, as hasheretofore been the custom inapparatus ofitheclass, but atcertainpointson gthe diaphragm, whereby a difierent anode of vibration is,established in filler diaphragm. In casevthe driving force is mpplied tothe apex, stress waves are developed in the materialand spread outwardlyfrom the apex'at equal speeds in alldirections. When the-driving forceis applied to .a point-other than ,the apex, stress waves are set up inthe material and radiate from the point of applicationof the drivingforce, but in this instance, ;a part of the wave travels towardtheapexinsteadof away fr0m it,resulting in a substantially different mode of'vibrationof the diaphragm and a substantially different characteristicof the radiated sound. This is particularly true when the driving forceis applied at a plurality of pointseand mechanically out-of phase.

In accordance with a further modification ,of my invention, I apply thedriving ,force =at'a pluralityof points on the line of intersectionformed by the two cones eitherat a pair of points mechani rllydifierent,or are more than 2 vpoints mechanically out of phase.

Referring now more particularly to Figures 1, 2 and 3; 1 designates arelatively large conical diaphragm of suitable material, such as paper,cardboard, wood, composition or even metal, adapted to be supported by asuitable base 2, carrying a stress plate 3, to which is secured apiezoelectric device 4, such for example, as a crystal of Rochelle saltexhibiting the well known hour glass configuration. One basal plane ofthe crystal is suitably secured to the stress plate 3, as by bolting, orcementing by the use of Rochelle salt melt, comprising Rochelle salt,from which the desired amount of water has been removed by heating it ata temperature above the melting point thereof. A second stress plate 5may be secured to the top basal plane of the crystal 4, and issuificiently long to extend outwardly on each side of the crystal soasto be capable of connection to thediaphragm 1, at points intermediatethe apex of the periphery thereof. Suitable driving rods 6 and '7 arefastened to the stress plate 5-on one end and to points 8 and 9 on thediaphragm, at the other end, which points may be suitably reinforced asby the application of Rochelle salt melt to the diaphragm at thesepoints. A pair of electrodes 10 and 11, shown diagramatically, are alsoprovided for the'purpose of impressing electrical oscillation at thecrystal device 4. The precise formand arrangement of these electrodes isnot, per se, part of this invention and any suitable arrangement maybeutilized. For example, one of the electrodes 10 may constitute a belt ofconducting *material, forming a loop around the crystal, intermediateltSi basal planes, while the other electrode 11, maybe an internalelectrode or may be formedby the plates3 and 5. The application ofelectrical oscillations to the electrodes 10 and11, causes thedevelopment of stresses in the crystal which .tend to rotate the stressplate 5 with respect to the stress plate ,3. V

The connection of he opposite ends" of stress plate 5 to the diaphragmope'rates'to set the same into vibration at points 8 and .9 with avibration which is mechanicallyout of phase The base 2, as will beunderstood, should be made to h ave a 'sufficiently large massso thatthestresses developed inf the crystal will be transmitted to the;atmosphere through'vibrations of the diaphragm.

Referring now'to Figures 4 and 5,1 have shown the. diaphragm asbeingfmade up of an incomplete cone 12, having its apex portion cutaway,andan apex'portion 13haVing its periphery secured to thelinner peripheryof the cone 12 to form a circularjline of the intersection 14. In thisinstance, the stress plate 5 issecureduponthe horizontal diagonal ofthe. circle of intersection 14, at

points 15 and 16 thereon It willbe seenthat vibrations are transmittedfrom these points cone 12 and inwardly to the apex of the cone 13.

In the arrangement shown in Figure 6, the diaphragm is substantially thesame but in this instance, the stress plate 3 is made sufficiently longso that the circle of intersection 14 may be attached at points 17 and18 to stress plate 5, and at points 19 and 20 to stress plate 3.

While I have shown and described certain preferred embodiments of myinvention, it will be apparent that modifications and changes may bemade without departing from the spirit andscope of my invention as willbe understood by those skilled in the art.

Iclaim:

1. A loud-speaker comprising a relatively large conical shaped diaphragmexposed on oneside-tounconfined air, the center of said diaphragm beingturned inwardly upon itself,and means for driving'said diaphragmfrompoints on opposite sides of: the center thereof. I

, 2. 'A loud speaker comprising a relatively large conical diaphragm, acentral conical portion for said diaphragm extending in a directionopposite to the normal direction of direction opposite to theinormaldirectionof said diaphragm, and means for'driving said diaphragmatpoints coincident with-the juncture of said inner central'conicalportion and said diaphragm. 4. A loud speaker comprising a relativelylarge symmetrical diaphragm exposed on one 7 side to vunconfined:air,and means for driving symmetrical points thereof 'in predetermineddifferentphase relation.

5. A loud speaker comprising a relatively large conical diaphragm, acentral conical portion extending from said diaphragm in a directionopposite to the normal directionof "said diaphragm, andmeans for drivingsaid diaphragm from points on the "circumference of a circle definedbythe intersection between said cone and the plane of intersection normalto the axis thereof between the conical diaphragm; and the centralconical portion thereof. v t j a 6. A loud speaker comprisingarelatively large conical diaphragm having 7 the apex thereof ,re-entrantinto the body and means connected to said diaphragm 'at a plurality ofpoints for actuating respective portionsof said diaphragm out of timephase with each other. p

7. A loud speaker comprisinga relatively large conical "diaphragm;having theapex outwardly to the periphery of thes'ect'ional' thereofformed re-entrant into the body, and

means for driving said diaphragm from points on the intersection betweenthe outer surface and the inner re-entrant surface.

8. A sound reproducing device comprising a diaphragm, piezo electricmeans for actuating said diaphragm and means connecting said piezoelectric actuating means and said diaphragm at a plurality of points foractuating portions of said diaphragm out of 1 time phase with respect toeach other.

Signed at New York city in the county of New York and State of New Yorkthis tenth day of March, A. D. 1927.

ALEXANDER McLEAN NICOLSON.

